in reply to How do I access values in a hash by two different keys?

If you keep filename as your key, you could write your loop as 

for my $i ( keys %{ $config->{item} } ) 
{
    print $config->{item}->{$i}->{id}, ": ";
    print $config->{item}->{$i}->{destination_dir}, "\n";
}

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If you need it sorted by id, it goes like this: 

for my $i (sort { $config->{item}->{$a}->{id} <=> $config->{item}->{$b
+}->{id} } keys %{ $config->{item} } ) 
{
    print $config->{item}->{$i}->{id}, ": ";
    print $config->{item}->{$i}->{destination_dir}, "\n";
}

[download]

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Re^2: How do I access values in a hash by two different keys?
by turbodizik (Initiate) on Jul 19, 2013 at 09:12 UTC
    It is a very good solution, thank you!
    But I have a question: Why this code works 
    for my $i ( keys %{ $config->{item} } ) 
{
    print $config->{item}->{$i}->{destination_dir};
}

    [download]
    and this one not?
    for (my $i=0; $i < 4; $i++ ) 
{
    print $config->{item}->{$i}->{destination_dir};
}

    [download]
    I mean, it is nearly the same... I just say how often the loop should go and then I access via the index {$i}. Or not?
    Even print $config->{item}->{1}->{destination_dir}; this one doesn't work...
    I just want to understand. Thank you again!
[reply]
[d/l]
[select]

      Have a look at your data structure using Data::Dumper: 

      use Data::Dumper;
print Dumper $config;

gives you

$VAR1 = {
          'item' => {
                      'AMEX' => {
                                'destination_dir' => 'test',
                                'id' => 0
                              },
                      'bla' => {
                               'destination_dir' => 'test1',
                               'id' => 1
                             },
                      'alb' => {
                               'destination_dir' => 'test2',
                               'id' => 2
                             }
                    }
        };

      [download]

      So $config->{item} represents a reference to a hash with keys "AMEX", "bla", and "alb". If you try $config->{item}->{1}->{destination_dir}; you are using a key that does not exist, the string "1".

      UPDATE: I probably should state explicitely that there is no numeric index in a hash and that there is no defined order of items in a hash that you can rely on.

[reply]
[d/l]
[select]
        Now I understand! :) Thank you very much!
[reply]

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